Dots in dot density maps do not represent the locations of things they represent a summary of data for a given area.ĭot density is an effective method to visualize concentrations of quantitative data. For example, a map of a state with dots representing locations of fast food restaurants would not be considered a dot density map. There are two types of dot maps, produced through very different techniques, but to similar effect: 1) point feature maps, based on point data representing the location of every individual in the population, and 2) choropleth dot maps, using the same kind of polygon/aggregate-attribute data used for choropleth maps, but showing the value of each district using a number of randomly placed dots rather than a solid fill color.Įach dot in a dot density map represents an aggregate of information. Thus, areas with more dots indicate higher density/concentration.

Each dot may represent either a single individual, or a representative group of individuals, and dots are placed according to the precise or estimated locations of these individuals or groups, usually using GIS data. Dot density maps can be a good alternative to choropleth maps because you can show the raw variable without normalizing it because the map viewer still gets an idea of how it is distributed. Dot density map showing concentrations of population 21+ in Ohio.Ī dot density map is a type of Thematic map that uses large numbers of dots or points to portray the relative geographic distribution of a population of some kind (e.g., people, livestock, businesses).

Us population density wall map thematic